1. Field of the Invention
This invention relates to a process for the catalytic production of substituted aryl sulfides. More particularly, this invention relates to a process for the production of alkoxy and phenoxy substituted aryl sulfides, especially substituted diaryl sulfides, wherein an alkali metal tetrafluoroborate catalyst is employed.
2. Background of the Invention
A wide variety of aryl sulfides, and in particular diaryl sulfides and di(alkaryl) sulfides, are known, the utilities of which are just as varied. For example, aryl and in particular diaryl sulfides are known to be useful as intermediates, especially for the preparation of insecticides, as plasticizers, high boiling solvents, heat exchange fluids, and hydraulic fluids.
A well known class of substituted aryl sulfides is that of the hydroxy substituted diaryl sulfides, or thiobisphenols, same having utility as intermediates or as oxidation inhibitors. One generally known process for preparing hydroxy substituted diaryl sulfides, or thiobisphenols, is by reacting a phenol with a sulfur chloride compound.
For example, U.S. Pat. No. 4,056,568 discloses the reaction of a 3,5-dialkyl phenol with a sulfur chloride compound to form a sulfenyl chloride. Subsequent reaction thereof with a phenol produces a diaryl monosulfide.
U.S. Pat. No. 3,718,699 discloses a process of preparing 4,4'-dithiobis(2,6-di-t-butylphenol). Said process comprises reacting 2,6-di-t-butylphenol with sulfur monochloride in the absence or presence of a catalytic amount of iron powder or a Lewis acid.
U.S. Pat. No. 3,129,213 discloses a process wherein an orthoalkylphenol is reacted with sulfur dichloride to form a reaction product suitable for use as an antioxidant and anti-wear agent. U.S. Pat. No. 3,057,926 discloses a process wherein an alkyl or alkoxy substituted phenol is reacted with sulfur dichloride. Alternatively, the process may comprise the reaction of an alkali metal salt of the substituted phenol with sulfur dichloride. Neither reaction, however, is conducted in the presence of a catalyst.
Similarly, U.S. Pat. Nos. 2,139,321; 2,370,756; and 2,971,968 disclose the preparation of thiobisphenols by reacting an alkyl phenol with a sulfur chloride compound in the absence of a catalyst.
U.S. Pat. No. 2,402,685, however, discloses reacting a phenol with sulfur dichloride in the presence of a "sulfurization catalyst" to produce a diaryl monosulfide product. Examples of suitable "sulfurization catalysts" include aluminum chloride, bismuth chloride, iron chloride, mercuric chloride, tin chloride, antimony chloride, tantallum pentachloride, titanium tetrachloride and zinc chloride.
While numerous processes are known for preparing hydroxy substituted aryl sulfides, the prior art is devoid, however, of a truly suitable process for the formation of aryl sulfide compounds, and in particular diaryl sulfides, wherein the aromatic rings are substituted, particularly in the para positions, with a more complex electron releasing group, such as an alkoxy or phenoxy. Such a process, particularly if given to high reaction rates and yields, would find ready acceptance by the industry for the preparation of such compounds, which find utility as percursors, stabilizers, plasticizers, etc.
Accordingly, it is an object of the instant invention to provide a process for the effective and efficient preparation of alkoxy and phenoxy substituted aryl sulfides.
It is another object of the instant invention to provide a novel process for the preparation of substituted diaryl sulfides, and in particular, diaryl sulfides substituted in the para positions with an alkoxy or phenoxy substituent.
Still another object of the instant invention is to provide a process for preparing diaryl sulfides in high yields, with high reaction rates, and with high selectivity.
These and other objects, as well as the scope, nature and utilization of the invention, will be apparent to those skilled in the art from the following description and the appended claims.